Try a 500 poundish av amp, its a myth about the quality of av amps in stereo not being as good as dedicated stereo amps.
Apart from giving alot more options - anolog or digital inputs, They offer the novelty of DSP functions for your entertainment. Set up is important though to get the best from them, turn all unused channels off, ensure speaker size is set to large and low frequencies are sent to the fronts. And if you want to really listen turn off the DSP effects. You can also bi-amp or bi-wire your front speakers.
AV amps usually have power supplys capable of handling at least 5.1 times 50wpc - it'll handle the dynamic swings in any music you present to it in stereo with more than enough head room.
in my experience while stereo amps do go louder (shouty) a well sorted av amp controls speakers better, you may be impressed with the stereo amp in a short test/demo but in a domestic set up av amps sound fine.
Yamaha usually do AV amps that are very capable in stereo.
I Have a Rotel ra - 1520 and an old Yamaha ax-620....... The yamaha sounds better in stereo....maybe its preference though.